Signaling apparatus



June 19, 1923.

D. G. M CAA SIGNALING APPARATUS Original Filed April 6. 1920 III A ATTORNEK Patented June 1%, W23.

DAVID G. McCAA, OF LANCASTER, PENNSYLVANIA, ASSIGNOR OF ONE-THIRD TOFED- ERAL TELEGRAPH COMPANY, OF SAN FRANCISCO, CALIFORNIA, A CORPORATIONOF CALIFORNIA.

SIGNALING APPARATUS.

Application filed April 6, 1920,.Seria1 No. 371,674. Renewed November 3,1921. Serial No. 512,572.

To all whom it may concern:

Be it known that- I DAVID G. MoCAA, a citizen of the United states,residing in the city of Lancaster, county of Lancaster, State ofPennsylvania, have invented a new and useful-Signaling Apparatus, ofwhich the following is a specification.

My invention relates to electrical communication of signals orintelligence, telegraphically, telephonically, or otherwise, by recourseto high frequency waves, whose energy is transmitted in electro-radiantform through the natural media between stations.

It is the object of my invention to render practically harmless in orsubstantially eliminate from radio receiving systems the effects ofnatural electricity, as atmospheric disturbances, static, strays, etc.,or other interfering electrical effects.

In accordance with my invention, and as described in my originalapplication Ser. No. 342,355, filed December 4, 1919, the. oscillationsin the radio receiving system corresponding with the undamped wavesreppresenting a desired signal and the oscillations present in, thereceiving system and corresponding with or due to static, atmospherics,strays or undesired signals, are caused to act through the employment ofa plurality of detectors differentially or in such wise upon the signaltranslatinge instrument, as a telephone, to produce no audible effect;and locally produced oscillations are so utilized, however, as toproduce beats with the oscillations representative of the desiredsignal, and these beats operate cumulatively upon the signal translatinginstrument to produce an audible signal, the locally producedoscillations so reacting with the other aforesaid oscillations in thereceiving system as toproduce in the signal translating instrument noaudible effect, or an effect which is small or not materiallyinterfering with the desired audible signal.

Further in accordance with my invention, the locally producedoscillations are adjust ed as to their amplitude in their reaction withthe oscillations in the receiving system representative of the desiredsignal and disturbing electrical effects whereby' the audibility of thebeats effected by the oscillations representing the desired signal isrendered sufficiently great compared with the audibility of the beateff'ects'due to the oscillations representing the disturbing effectsthat the desired signal is readily heard Fig. 1 is a diagrammatic viewof receiv ing apparatus embodying my invention and involving primarybeats.

Fig. 2 is a diagrammatic view of a modification involving both primaryand secondary beats.

Referring to Fig. 1, A represents generically any receiving conductor,as an antenna, of open circuit, loop, coil or any other suitable type,or a line conductor extending to the receiving station.

In series between the antenna and earth or other capacity E are seriallyconnected the adjustable loading inductance L and the adjustable primaryP of an oscillation transformer, a variable condenser being connected inparallel with L and P if suitable or desirable. particularly for tuningto the frequency of the received signal waves.

Inductively coupled with the primary P is the adjustable secondary Sconnected in a circuit with adjustable inductance L and variablecondenser C for bringing said circuit into resonance with the circuit orpath .of the primary P.

the coils S? and S are connected, respectivebridging the anode circuitbattery B, the circuit being completed to the hot cathode or filament 7,the latter being traversed by current from the battery 6, the currentstrength being variable by the adjustable resistance r. Similarly, theanode a} co-acting with grid g has its external circuit con nectedthrough the primary P and the variable resistance r.'

- A. second connection is made from the circuit of the secondary S,preferablyfrom the other terminal of the condenser C, to the cathode orfilament f.

The primaries P and P produce equal and opposite effects upon thesecondary S which may be bridged by the variable tuning condenser C andin whose circuit is connected the translating instrument, as a telephoneT. With the primaries P, P and secondary S may be employed, if suitableor desirable, the magnetizable core structure 0.

The apparatus as thus far described operates asfollows: v

The energy received upon the antenna structure A and through the coils Sand S impress equal electro-motive-forces upon the grids g and g, whicheffect equal current changes in the circuits of their associated anodes.The current changes in the primaries P and P are therefore equal, andsince these primaries oppose each other in their inductive effects uponthe secondary S no current'is induced in the secondary S and there is noresponse by the telephone T. In other words, the effects of the receivedenergy and any effects, oscillatory or otherwise, produced byatmospheric disturbances, natural eleetricity, strays, static, etc.,have no effect upon the telephone T.

To vitalize the system and to cause response to the received signalenergy to the substantially complete elemination or ex clusion of allother disturbing effects, there is inductively related to thesecondaries S and S the primary P so connectedor disposed as to affectthe secondaries S and S oppositely and substantially equally. The coil Pis preferably rotatable toward and from the position in which maximuminductive effects are produced upon the secondaries S and S wherebythose inductive effects are variable.

The primary P is traversed by oscillations preferably of radio orinaudible frequency, differing from the frequency of the receivedenergy, produced by the thermionic oscillator V or any other othersuitable source of oscillations, as an arc, dynamoelectric generator,etc.

When the primary P istraversed by oscillations as aforesaid, theoperation is as follows:

The oscillations in the secondaries S and S due to the received energyreact with the masses oscillations induced therein by the primary P toform beats which for telegraphy are of audible frequency and fortelepheny of inaudible frequency. 'The beats in the secondaries S and Sare opposite in phase and substantially equal, with the result that thebeat electro-motive-forces impressed upon the grids g and 9 cause thecurrent in the primary P to change in one sense while the current in theprimary P changes in opposite sense, and to equal extent with the resultthat the primaries P and P? as regards the best effects operatecumulatively upon the secondary S whose circuit may be attuned to thebeat frequency by the condenser C and which produces current of beatfrequency in the telephone T, which reproduces sound of beat frequency,the sound being of audio frequency in the case of tele raphy and beingspeech in the case of telep' ony when the beats era of inaudible.frequency. r

The effects of atmospheric disturbances, static, strays. etc. are suchas not to react effectively with the oscillations induced by primary Pin the secondaries S and S the disturbing effects being balanced out asregards the detector action of the thermionic device V or otherrectifying or equivalent detecting means, while the received signalenergy reacts to produce the beats aforesaid, which makes possible thereception of desired signal energy.

The rotation of primary P and adjustment of condenser C makes possiblerelatively different effects. With the condenser C adjusted to zero orsubstantially zero capacity, and the coil P rotated to such positionthat its inductive effect upon S and S is very small, weak locallyproduced electro- -motive-forces are impressed upon the grids g and g.This relation is desirable in the case of weak received signals duringexistence of strong static or other disturbances. Or the condenser C maybe adjusted to such capacity as to tune the circuit of the secondaries Sand S to the locally produced oscillations and the coil P rotated toposition to strongly affect coils S and S this latter relation beingsuitable for a condition when 1 received signaling energy is relativelystrong.

It will therefore be apparent that, as in my aforesaid application Ser.No. 342,355. the desirable effects are procured by suitably relating theamplitude of the locally produced oscillations to the amplitude of thereceived signal energy. Preferably the amplitude of oscillations inducedin the coils S and S by the primary P is adjusted, as by adjusting theposition of the coil P, or by any other equivalent means, to substantialequality with the amplitude of the oscillations in coils S and S due tothe received energy. With this relation existing, weak signals arereadily receivable through strong static or other disturbances, theratio of the amplitude of the current in coils S and S induced thereinby the primary P being small as compared with the amplitude of thecurrent in the coils S and S due to the strong static o otherdisturbances. Accordingly, the beat effect as between received signalenergy and the locally produced energy is of a character more suitablefor affecting the telephone T through the couplings P, P and S than theimperfect beat effect due to strong static or other disturbancesreacting with the locally producedososcillations; in other words, thesustained waves of the received energy affect the tele phone T only bybeat effect, while the strong static simultaneously occuring producesimperfect beat efi'ect, the static effects operating chiefly by'detectoraction which is substantially perfectly balanced out, and such balanceis but slightly disturbed by the presence of weak locally producedoscillations.

Accordingly, it is desirable, as above stated, to cause the amplitude ofthe locally produced oscillations to be substantially equal to theamplitude of the oscillations representing therdesired signal, wherebyin their react-ion in the production of beats the beat-representingcurrent fluctuates between zero value and a value substantially twicethe amplitude of the oscillations representing the received signal. Ifthe oscillations simultaneously existing in the receiving circuit due toreceived energy other than that of the desired signal are ofrelativelygreaten amplitude, though of the same frequency as theoscillations representing the desired signal. the reaction with thelocally produced oscillations of amplitude substantially equal to theamplitude of the weaker received signal oscillations causes beats-whichare imperfect in the sense that the beat-representin r current fluctatesbetween magnitudes equai to the sum of the amplitude of the locallyproduced oscillations and the amplitude of the oscillations'of thedistrubing effects and a minimum value which is the difference be-.tween those amplitudes. That is to say, the

. change in amplitude of the beat-representing current is substantiallythe same as the change between zero and maximum amplitude of thebeat-representing current due to the oscillations representing thedesired signal. In consequence,"the effect upon the signaltransl'atinginstrument, as a telephone, may be about the same as regards the effectsof the desired signal and the disturbances, with the result that therelatively weak signal produces an effect substa-ntially equal to theconsiderably stronger disturbing effect. In other words, the ratio ofthe effect produced by the received signal j to the effect produced bythe disturbances is 'static or other disturbances.

beat effects may be produced.

increased, so that the signal may be readily read, though the static oother disturbances be of an amplitude many times the amplitude of therelati"ely weak received signal. Itwill be understood, also, that thebeats produced with the oscillations representing the static, strays.atmospherics and the like are at a disadvantagein theireffect upon thesignal translating instrument because such oscillations are decadent,and relatively imperfect beats are produced which affect the signaltranslating instrument to relatively less extent that the perfect beatsproduced with the undamped oscillations representing the desired si al.

It will be understood that the condenser C is not essential; itis-employed, as stated, when it is suitable or desirable for tuning thecircuit of the coils S and S to the frequency of the locally producedoscillations.

While the foregoing has dealt with the reception of signals representedby un-' the apparatus ,on the coils S and S bythelocally producedoscillations is made weak, in which case both the disturbing static orother effects and the received signals are manifested in the telephoneT, but are of equal strength or amplitude. and for that" reason thesignals are readily distinguishable from the In this case, while .staticis not eliminated, its effect is so greatly reduced as to permit readingof the spark signals.

In Fig. 2 there is illustrated an arrangement whereby both primary andsecondary In this case the electro-motive-forces in the circuit of thesecondary S, tuned to the sustained received energy by adjustableinductance L and variable condenser C are impressed upon the grid g ofthe thermionic oscillator V",

whose variable condensers are and producing oscillations of IEIdIO OIinaudible frequency differing from the frequency of the received energyto produce beats of inaudible frequency in the case of telegraphy and inthe case of telephony. The beat curary S to the remainder of theapparatus is similar to the connection of the secondary S with theremainder of the apparatus of Fig. 1, the circuit of secondary 8 beingaperiodic. There exist in the secondaries S and S currents of beatfrequency, and the oilcuit of these secondaries may be turned to thefrequency of the oscillations produced by V by the variable condenser Cit being understood that condenser C may be omitted, in which case saidcircuit i aperiodic. The oscillator V again produces oscillations of afrequency causing production in the grid circuits of the secondaries Sand S of secondary beats of audible frequency for telegraphy andinaudible frequency fortelephony.

When the oscillator V is inoperative, the effects of the received energyand the beats produced therewith by the oscillator V upon the secondaryS and telephone T is zero. l/Vhen the oscillatorV is in operation,however, the secondary beats, which are opposite in phase andsubstantially equal, are caused by primaries P and P cumulatively toaffect the secondary S with resultant production of sound by thetelephone '1, such sound being an audible note for telegraphy and speechin the case of telephony when the secondary beats are aboveaudib-ility.-

By this arrangement also the efi'ects of static" or, other disturbancesare eliminated, while the desired signal energy causes response by thetelephone T.

The system of F' to that of Fig. 1, except that the secondaries S and Sare traversed by primary beat currents which react with the oscillationsinduced therein by the primary P to produce secondary beats. The effectof static or like disturbance-s is to cause the production in thecircuit of the primary P of great current changes of audible frequencyas a result of detector action of the thermionic device V and suchaction overshadows any reaction of the static energy with theoscillations locally produced by the oscillator V In consequence, thereis induced in the circuit of the secondary S like,

currents of large amplitude of audio frequency, such audio frequencybeing, due to the .natureof static effects, relatively low. Suchrelatively low audio frequency in the coils S S will not react with theoscillations locally produced by the device V to produce a beat effectaudible in the telephone T. But the sustained signal waves produce beatsof inaudible frequency with the oscillations from the oscillator V withtransfer to the circuit of the secondary S of beat currents of similarinaudible frequency, which approaches the frequency of the oscillationsproduced by the device V far more closely than the aforesaid low 1g; 2is in general similar audio frequency due to the static effects.

The result is the production 'of secondary beats of audible frequencyfor telegraphy and inaudible frequency for telephony which affect thetelephone T, which reproduces the signals.

It will be understood that between the coils S S and the antenna circuitor path,

it will be understood that such inductive coupling may be supplanted byaconductive coupling, And similarly, in Fig. 2, in lieu of the inductivecoupling if, S a conductive coupling may be made between the circuitcontaining coils S, S and the, anode or plate circuit of the thermionicdevice V What I claim is:

v 1. Apparatus for receiving signals repre I sented by undamped waves ofradio frequency and for reducing the disturbing effects ofsimultaneously received energy comprising a receiving structure, signaltranslating means, detecting circuits differentially affecting saidsignal translating means, a local source producing oscillations reactingwith the received oscillations representing the desired signal and .thesimultaneously received energy to produce opposing beats cumulativelyaffecting said signal translating means, and means for adjusting theamplitude of said locally produced oscillations in their reaction withsaid oscillations for relatively increasing the effect upon said signaltranslating means of the beats representing the desired signal.

2. Apparatus for receiving signals represented by undamped waves ofradio frequency and for reducing the disturbing effects ofsimultaneously received energy comprising a receiving structure, signaltranslating means, detecting-rectifying circuits differentiallyaffecting said signal translating means, a local source producingoscillations reacting with the received oscillations representing thedesired signal and the simultaneously received energy to produceopposing beats cumulatively affecting said signal translating means, andmeans for adjusting the amplitude of said locally pro-v ducedoscillations in their reaction with said oscillations for relativelyincreasing the effect upon said signal translating means of the beatsrepresenting the desired signal.

3.' Apparatus for receiving signals represented by undamped waves ofradio frequency and for reducing the disturbing effects ofsimultaneously received energy comprising a receiving structure, signaltranslating means, detecting circuits differentially afi'ecting saidsignal translating means, a

senting the desired signal and the sin1ultanc ously received energy toproduce opposing beats cumulatively affecting said signal translatingmeans, said primary and secondary windings being relatively movable foradjusting the amplitude of the oscillations induced in said se ondarywindings for relatively increasing the eliect upon said signaltranslating means of the beats-representing the desired signal.

4. Apparatus for receiving signals represented by undamped waves ofradio frequency and for reducing the disturbing cf 't'ects ofsimultaneously received energy comprising a receiving structure, signaltranslating means, detecting circuits differentially affe ting saidsignal translating means. a secondary winding For each of said circuits,a primary winding coacting with said secondary windings, and a localsource producing oscillations in said primary winding rcacting with thereceived oscillations representing the desired signal and thesimultaneouslv received energy to produce opposing beats cumulativelyaffecting said signal translating means, said primary winding beingrotatable relatively to said secondary windings for adjusting theamplitude of the oscillations induced in said secondary windings forrelatively increasing the effect upon said signal translating means ofthe beats representing the desired signal.

5. Apparatus for recelving slgnals reprcsei'ited by waves of radiofrequency comprising a receiving conductor, aplurality of windings. aconductive connection from a terminal of each of said windings to'acircuit affected by the received energy, detectors each having aterminal connected to anothcr-terminal of each of said windings, theother terminals of said detectors conductivcly connected to saidcircuit, signal translating means, a source of oscillations prodlu ingin said windings oscillations reacting with received energy to producetherein opposing beats. means oo-operating with said detectors and saidsignal translating means rendering said beats cumulative upon saidsignal translating means and the received energy of substantially noefiect upon said signal translating means, and means for attuning acircuit including said windings to the frequency of said oscillations.

6. Apparatus for receiving signals represented by waves of radiofrequency comprising a receiving conductor, a plurality of secondarywindings. a conductive connect-ion from a terminal of each of saidsecondary windings to a, circuit affected by the received energy,detectors each having a terminal connected to another terminal of eachof said windings, the other terminals of said dotectors connected tosaid circuit, signal translating means, a primary winding movablewithrespect to said secondary windings, a source of oscillationsassociated with said primary winding producing therein oscillations of afrequency differing from the frequency of the received energy, means forrendering the resultant beats cumulative upon said signal translatingmeans and the received energy of substantially no efiect upon saidsignal translating means, and means for attuning a circuit includingsaid secondary windings to the frequency of said oscillations.

7 Apparatus for receiving signals represented by waves of radiofrequency comprising a receiving conductor, a plurality of windings, aconductive connection from a terminal of each of said windings to acircuit affectedby the received energy, thermionic detectors oneterminal of whose grids is connected with another terminal of each ofsaid windings and whose electron-emitting means are connected to saidcircuit, signal translating means. means for impressing upon saidwindings oscillations reacting with received nergy to produce opposingbeats, means co-acting with the anode circuits of said detectors andsaid signal translating means for rendering said beats cumulat-ive uponsaid signal translating means and the received energy of no efieot uponsaid signal translating means, and means for attuning a circuitincluding said windings to the frequency of said oscillations.

8. Apparatus for receiving signals represented by waves of radiofrequency comprising a receiving conductor, a source of oscillationsassociated therewith and react ing with the received energy to producebeats, a plurality of windings each having one terminal conduc-tivelyconnected with a circuit traversed by said beats, a plurality ofdetectors each having one terminal connected' to another terminal ofeach of said windings. the other terminals of said detectors connectedwith said circuit, a second source of oscillations producing in saidwindings opposing beats. signal translating means, means associated withsaid detectors and said signal translating means rendering said secondnamed beats cumulative upon said signal translating means and said firstbeats of substantially no efiect upon said signal translating means, andmeans for attuning a circuit including said windings to the frequency ofsaid second named oscillations. M

' 9. Apparatus for receiving signals represented by waves of constantradio frequency and for reducing the disturbing effects ofsimultaneously received energy,

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comprising a receiving circuit, means for attuning said circuit to thefrequency of the waves representing the desired. signal, whereby theamplitude of the oscillations representing the desired signal isincreased and the oscillations representing the simultaneously receivedenergy have a frequency corresponding with the frequency of saidoscillations, means for locally producing oscillations reacting with theoscillations representative of the desired signal and the oscillationsrepresenting the simultaneously received energy, the frequency of thelocally produced oscillations being such that the resulting beats have aconstant super-audible frequency, signal translating means, detectingcircuits differentially affecting said translating means under theinfluence of said su er-audible beats, and a local source producingoscillations reacting with said super-audible beats to produce secondaryopposing beats of constant frequency cumulatively affecting said signaltranslating means.

10. Apparatus for receiving signals represented by waves of constantradio frequency and for reducing the disturbing effects ofsimultaneously received energy, comprising a receiving circuit, meansfor attuning said circuit to the frequency of the waves representing thedesired signal, whereby the amplitude of the oscillations representingthe desired signal is increased and the oscillations representing thesimultaneously received energy have a frequency corresponding with thefrequency of said oscillations, means for locally producing oscillationsreacting with the oscillations rep resentative of the desired signal andthe oscillations representing the simultaneously received energy, thefrequency of the locally produced oscillations being such that theresulting beats have a constant super-audible frequency, signaltranslating means detecting circuits differentially afiecting saidtranslating means under the influence of said super-audible beats, and alocal source producing oscillations reacting with said super-audibleheats to produce secondary opposing beats of constant audible frequencycumulatively affecting said signal translating means.

ll. Apparatus for receiving signals represented by waves of radiofrequency and for reducing the disturbing eflects of simultaneouslyreceived energy, comprising a receiving circuit, means for attuning saidcircuit to the frequency of the waves repre senting the desired signal,whereby the amplitude of the oscillations representing the desiredsignal is increased and the oscillations representing the simultaneouslyreceived energy have a frequency corresponding with the frequency ofsaid oscillations,

means for locally producing oscillations reacting with the oscillationsrepresentative of the desired. signal and the oscillations representingthe simultaneously received energy, the frequency of the locallyproduced oscillations being such that the resulting beats have asuper-audible frequency, signal translating means, detecting circuitsdifierentially afiecting said translating means under the influence ofsaid super-audible beats, a local source producing oscillations reactingwith said super-audible beats to produce secondary opposing beatscumulatively affecting said signal translating means, and means foradjusting the amplitude of the oscillations of said secondary sourc forrelatively increasing the effect upon said signal translating means ofthe secondary beats representing the desired signal.

12. Apparatus for receiving signals represented by waves of radiofrequency and for reducing the disturbing efiects of simultaneouslyreceived energy, comprising a receiving circuit, means for attuning saidcircuit to the frequency of the waves representing the desired signal,whereby the amplitude of the oscillations representing the desiredsignal is increased and the oscillations representing the simultaneouslyreceived energy have a frequency corresponding with the frequency ofsaid oscillations, means fo locally producing oscillations reacting withthe oscillations representative of the desired signal and theoscillations representing the simultaneously received energy, thefrequency of the locally produced oscillations beingsuch that theresulting beats have a super-audible frequency, signal translatingmeans, detecting circuits differcntially affecting said translatingmeans under the influence of said super-audible beats, a local sourceproducing oscillations reacting with said supcr-audible beats to producesecondary opposing beats of audible frequency cumulatively affectingsaid signal translating means, and means for adjusting the amplitude ofthe oscillations of said secondary source for relatively increasing theefi'ect upon said signal translating means of the secondary beatsrepresenting the desired signal, a

13. Apparatus for receiving signals represented by waves of radiofrequency and for reducing the disturbing effects of simultaneouslyreceived energy, comprising a receiving circuit, means for attuning saidcircuit to the frequency of the waves representing the desired signal,whereby the amplitude of the oscillations representing the desiredsignal is increased and the oscillations representing the simultaneouslyreceived energy have a frequency corresponding with the frequency ofsaid oscillations, signal translating means, 'detccting circuitsdifferentially affecting said signal translating means, a local sourcellOG not

are

lSlll producing oscillations having an amplitude approximately equal toand reacting with the aforesaid oscillations representing the desiredsignal to produce opposing beats of constant frequency cumulativelyaffecting said signal translating means, whereby the desired signal ismore readily distinguished from the efiects produced by saidsimultaneously received energy.

14. Apparatus for receiving signals represented by waves of radiofrequency and for reducing the disturbing effects of'simultaneouslyreceived energy, comprising a receiving circuit, means for attuning saidcircuit to the frequency of the waves representing the desired signal,whereby the amplitude of the oscillations representing the desiredsignal is increased and the oscillations representing the simultaneouslyreceived energy have'a frequency corresponding with the frequency ofsaid oscillations, signal translating means, detecting circuitsdifferentially affecting said signal translating means, a local sourceproducing oscillations reacting with the aforesaid oscillations toproduce opposing beats of constant audible frequency cumulativelyaffecting said signal translating means, whereby the desired signal ismore readily distinguished from'the effects produced by saidsimultaneously received energy.

15. Apparatus for receiving signals represented by waves of radiofrequency and for reducing the disturbing effects of simultaneously receved energy, comprising a receiving circuit, means for att-uning saidcircuit to the frequency of the waves representing the desired signal,whereby the amplitude of the oscillations representing the de-.

sired signal is increased and the oscillations representing thesimultaneously received energy have a frequency corresponding with thefrequency of said oscillations, signal translating means, detectingcircuits differentially affecting said signal translating means, a localsource producing oscillations reacting with the aforesaid oscillationsto produce opposing beats cumulatively affecting said signal translatingmeans, whereby the desired signal is more readily distinguished from theeffects produced by said simultaneously received energy, and means foradiusting the amplitude of said locally produced oscillations in theirreaction with said oscillations for increasing relatively to the effectof said simultaneously received energy upon said signal translat ngmeans the effect upon said signal translating means of the beatsrepresenting the desired signal.

16. Apparatus for receiving signals represented by waves of radiofrequency and for reducing the disturbing effects of simultaneouslyreceived energy, comprising a receiving circuit. means for attuning saidcircuit to the frequency of the waves representing the desired signal,whereby the amplitude of the oscillations representing the desiredsignal is increased and the oscillations representing the simultaneouslyreceived energy have a frequency corresponding with the frequency ofsaid oscillations, signal translating means, de'tectingcircuits diffenentially affecting said signal translating means, a local sourceproducing oscillations reacting with the aforesaid oscillations toproduce opposing beats of audible frequency cumulatively affecting saidsignal translating means, whereby the desired signal is more readilydistinguished from the effects produced by saidsimultaneously receivedenergy, and means for adjusting the amplitude of said locally producedoscillations in their reaction with said oscillations for increasingrelatively to the effect of said simultaneously received energy uponsaid signal translating means the effect upon said signal translatingmeans of the beats representing the desired signal.

1.7. Apparatus for receiving signals represented by waves of radiofrequency and for reducing the disturbing effects of simultaneouslyreceived energy, comprising a receiving circuit, means for attuning saidcircuit to the frequency of the waves representing the desired signal,whereby the amplitude of the oscillations representing the desiredsignal is increased and the oscillations'representing the simultaneouslyreceived energy have a frequency corresponding with the frequency ofsaid oscillations, signal translating means, detecting circuitsdifferentially affecting said signal translating means, a local sourceproducing oscillations reacting with the aforesaid oscillations toproduce opposing beats cumulatively affecting said signal translatingmeans, whereby the desired signal is more readily distinguished from theeffects produced by said simultaneously received energy, and means foradjusting the amplitude of said locally produced oscillations in theirreaction with said oscillations representing the desired signal tosubstantial equality with the amplitude of said oscillationsrepresenting the'desired s gnal. whereby the ratio of the magnitude ofeffect upon said signal translating means of the beats representing ergyhave a frequency corresponding with the frequency of said oscillations,signal translating means, detecting circuits difierentially affectingsaid signal translating means, a local source producing oscillationsreacting with the aforesaid oscillations to produce opposing beats ofaudible frequency cun'iulatively affecting said signal translatingmeans, whereby the desired signal is more readily distinguished from theeffects produced by said simultaneously received energv. and means foradjusting the amplitude of said locally produced oscillations in theirreaction with said oscillations representing the desired signal tosubstantial equality with the amplitude of said oscillationsrepresenting the desired signal, where by the ratio of the magnitude ofeii'ect upon said signal translating means of the beats representing thedesired signal to the magnitude of effect upon said signal translatingmeans of said simultaneously received energy is increased.

19. Apparatus for distinguishing between oscillations representing adesired signal and oscillations ot' the same frequency but greateramplitude, comprising signal translating means, detecting circuitssimilarly in fluenced by said oscillations and difierentially related tosaid signal translating means, a local source producing oscillationsreacting with said oscillations of diil'erent amplitudes to produceopposing beats cumulatively affecting said signal translating means, andmeans for adjusting the amplitude of said locally produced oscillationsin their reaction with said oscillations of ditlerent magnitudes to amagnitude materially less than the magnitude of the amplitude of saidoscillations of greater amplitude and approaching equality with themagnitude of amplitude of the oscillations representing the desiredsignal, Whereby the "edect upon said signal translating means of thebeats representing the desired signal is increased.

20. The method of distinguishing between a desired signal represented byundamped electro-radiant energy and aperiodic or decadent energysimultaneously existing in the natural media, which comprises convertingthe electro-radiant energy into sustained oscillations and saidsimultaneously existing energy into decadent oscillations of the samefrequency, causing locally produced oscillations of different frequencyto react with said sustained oscillations and said decadent oscillationsto produce beats of constant audible frequency having differentcharacteristics, impressing said sustained and decadent oscillationsupon different circuits, impressing said beats in opposite senses uponsaid circuits, causing the effects of said oscillations in said circuitsto substantially nullify each other, and

masses cumulating and translating the efiects of said beats upon saidcircuits.

21. The method of distinguishing between oscillations representing adesired signal and oscillations of the' same frequency but of greateramplitude, which comprises causing locally produced oscillations ofdifferent frequency to react With said oscillations of differentamplitudes to produce beats, graduating the amplitude of said locallyproduced oscillations to substantial equality with the amplitude of saidoscillations representing the desired signal and differing greatly fromthe amplitude of said oscillations of greater amplitude, impressing saidoscillations of difierent amplitudes upon ditferent circuits, impressingsaid beats in opposite senses upon said circuits, causing the effects ofsaid oscillations in said circuits to substantially nullify each other,and cumulating and translating the efiects of said beats upon saidcircuits. v

22. Apparatus for receiving signals represented by undamped Waves ofradio frequency and for reducing the disturbing etfeots ofsimultaneously received energy, comprising a receiving circuit, meansfor attuning said circuit to the frequency of the waves representing thedesired signal, signal-translating means, detecting circuitsdifferentially affecting said signal-translating means, a local sourceproducing oscillations reacting with the osclllatlons representative ofthe desired signal to producev opposing beats of constant frequencycumulatively afiecting said signal -translating means, means foreiiecting an amplitude of the locally produced oscillations in producingsaid beats diflering from the amplitude oi the oscillations representingthe undesired received energy and more nearly equaling the amplitude ofthe oscillations representing the desired signal, whereby the ratioofthe effects upon said signal-translating means produced by the desiredsignal to the effects upon said signal-translating means produced by theundesired received energy is materially increased 23. In the art ofreceiving signals represented in transmission by undampedelectro-radiant energy waves, the method of increasing'the ratio of theeffects due to the desired signal to the eil'ects dueto static andsimilar natural electrical disturbances, which comprises locallyproducing oscillations of frequency differing vfrom the frequency of thereceived energy and of the oscillations produced by the staticdisturbance, causing the locally produced oscillations to react with theoscillations representing the desired signal" to produce beats ofconstant frequency and While so reacting to have an amplitude dilleringfrom" the amplitude of the oscillations due to the static disturbanceand more nearly equal to the amplitude of till Jltltl the oscillationsrepresenting the desired signal, impressing the oscillations due to thedesired signal and due to the static disturbance upon a pair ofcircuits, impressing said 5 beats in oppositesenses upon said circuits,causi the effects of said oscillations in said circuits to substantiallynullify each other, and cumulating and translating-the effects of saidbeats upon said circuits.

In testimony WhereofI have hereunto affixed my signature this 2nd day ofApril, 1920. v v

. DAVID G. MOCAA.

